The Stellaris (and by extension likely Stratus/Starlett) has an uncanny synergy with the Utopia. Comparing the Bifrost 2 to the Wavedream, technical differences notwithstanding, I can see where the mellow / lack of bite observation comes from, but it's slight and not the variable I'd optimize for given everything else. Piercing stuff will still sound piercing (especially with the Utopia!), just not every time strangely and somewhat depending on the record. I will say that Wavedream + Stellaris + HD6xx sometimes feels like too much of a good thing on the inner bloom / warmth, but that's complaining on a high level.